1/10 ECX Ruckus 4x4 Build

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Bear with me, trying to edit this one to work

Vivaton 29mm (EXB) spur is here. 44T versus the 50T that was on it. 47mm OD vs 53mm OD
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One immediately noticeable problem is the pinion I have on it (I think its a 14T) isn't large enough to mesh because of the motor mount geometry. I ordered a set of bigger options.
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But it picks up the clearance that I needed, by a mile
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Those bearing races arrived (and the aluminum center support). With the top plate I have now ghetto rigged on there I have no way to bolt the supports to it, but that proved to not be a problem. They stayed in place all on their own due to how the parts are machined.
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@Greywolf74 how is that?
I just viewed the thread from my wife's phone, who is not logged in to either forum, and all the pics seem to show up fine? This forum's format forces me to attach them in full size there is no "Insert Thumbnail" option
 
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Bear with me, trying to edit this one to work

Vivaton 29mm (EXB) spur is here. 44T versus the 50T that was on it. 47mm OD vs 53mm OD
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One immediately noticeable problem is the pinion I have on it (I think its a 14T) isn't large enough to mesh because of the motor mount geometry. I ordered a set of bigger options.
C6C0F9B6-EB53-406D-832F-E9DE9D0FE72C.jpeg


But it picks up the clearance that I needed, by a mile
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Those bearing races arrived (and the aluminum center support). With the top plate I have now ghetto rigged on there I have no way to bolt the supports to it, but that proved to not be a problem. They stayed in place all on their own due to how the parts are machined.
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All you have to do is add the pics to your post here and insert them. They will insert into the post wherever the cursor is. No need for external linking.
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All you have to do is add the pics to your post here and insert them. They will insert into the post wherever the cursor is. No need for external linking.
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Yeah, that's how I did the last post, the one that starts with the Vivaton spur. Can you see that post ok? Once the file(s) are attached, they are shown in preview along the bottom, with an "Insert" option. On other forums (like the sister ECX forum), when you click that you get either Insert Thumbnail or Insert Full Size. There is no Insert Thumbnail option here.
 
Yeah, that's how I did the last post, the one that starts with the Vivaton spur. Can you see that post ok? Once the file(s) are attached, they are shown in preview along the bottom, with an "Insert" option. On other forums (like the sister ECX forum), when you click that you get either Insert Thumbnail or Insert Full Size. There is no Insert Thumbnail option here.
It's the same here. Click insert, then click full size.
 
It has been an up and down few days of testing (more ups, luckily). I had a chance to get it out much later at night the same day as the last for a second session (I didn't have enough free time to tear it down and do anything meaningful), and it did well, though the ESC got a little warm. When we took it out just to walk around our daily walk of the property that we do, it actually hit the thermal cutoff. Of all the things we weren't carefully inspecting with basically a ground up build, I never would have thought to really watch the motor and esc temps (I'm talking about fifteen minutes of 10% throttle walking speed). I pulled the motor wires out, and two of the extensions were bent really badly at the banana plug.
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I resoldered them and put new heat shrink on and ran it again, this time 5 mins or so at 25% throttle, checking often. No real change to be honest.
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You can actually see where the ESC got the wires so hot it melted some of the solder and dripped down. These are 4mm banana on a 12AWG wire, and the wires or the wire extensions do not get hot, just the ESC. I did some reading and people were saying it's the low throttle position coupled with the really tall gearing, on grass, now with the bigger front tires (I swapped to Trenchers at all 4 corners to see how it affected the handling). Previously when we had too-much-drag problems from grass, it was the motor that would get hot not the ESC. Motor is barely warm to the touch, 95F on the gun.
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Changing the gearing really isn't an option, I'm limited on both pinion and spur by space constrictions. This is about the "shortest" ratio that will fit. I decided to relocate the ESC to an area where I could completely eliminate the extensions, I put a 3S battery in it instead of the 4S, and I went out and found a nice empty parking lot to run it (less rolling resistance). I also tried to get in some higher throttle positions, internet info was saying low throttle builds ESC heat). so I just rolled into it at speed. A little barrel roll from not having enough brake ejecting a shock bolt ended the session, but I got 10 or so passes in. ESC still got to 145 on the gun, but took a lot longer to get there. I'm inclined to say the car is just overgeared for the combo in it right now. Overall though, did decently with some steering adjustments, and having a rollover at speed like that and nothing catastrophically breaking is encouraging.
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Put it back together at home, ran it on grass and basically confirmed the diagnosis. It does better for sure on 3S. At one point, hit a decent bump and the XO-1 front protrusion dug into the ground at speed, sending it cartwheeling. Other than breaking the nose, it bascially ripped the bolt that holds the front pin retainer in (it only goes into plastic in the diff) on both the front and rear). So I need to add find a solution to that, plus stiffen up the front suspension (and try and raise it).
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We found the missing nose piece LOL

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We also began to have an issue with the rear driveshaft popping out. What was odd is that there wasn't enough play in everything to move it back in, I had to unbolt the top chassis brace and loosen the diff from below to get it back in both times

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That's when I noticed the missing screw out of the rear tie bar and took everything apart to look. What was happening was once the rear tie bar was loose, the diff case was seperating in half allowing the pinion and the diff cup to slide backwards out of position, creating enough room for the driveshaft to slide out. This is the downside to shakedown runs when everything isn't bolted up 100%...if I had all 4 bolts in the diff housing like it should have been, it wouldn't have been relying on that one single m3 tie bar bolt at the bottom to hold it together. You can see where the diff housing took damage as the pinion, bearing, and diff cup got loose and came out of round. I threw some red grease in there while I was putting it all back together.

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Having learned my lesson and having the rear apart now, I drilled and tapped the diff housing bolt holes out to m4 so I could run one real long bolt from the bottom to sandwich the chassis plate, the diff mount, and the diff housing together. There are now 4 bolts from the underside (two for each half) and two m3 bolts at the top holding the housing together, and it hasn't been a problem since

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Despite finding these "little" issues, it's going pretty well. We managed 37 on grass, which is right around where it was on 3S and 4S on the stock style drivetrain. The damage from the rollover that broke the front nose I think knocked the front control arm pin plate out of whack too and pulled the threads out, because we would later lose it somewhere in the grass. Being that the gearing is not optimized, I would say absolutely we were losing speed on the stock style stuff because parts were clearly not holding up to the power. This is the same battery, same motor, same ESC, same tires, even same crappy axles, only difference is center diff vs slipper clutch and the front and rear driveshafts/diffs. I would suspect we are still losing something in the slop still in the center driveshafts and the terrible axles on it now. Someone is pretty pleased with our progress, we found a new big spot a few minutes away from his preschool.

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Going to do another teardown and fix some small stuff, hopefully next time out we are making full power passes.
 
A lot has been happening lately with life and I just haven't had time to keep the thread up to date. While looking for other stuff we found a killer local deal on a max8 + 4274 2200kv combo. A few scratches on the can and a decent dent in one of the caps but appears to function fine. Made up a quick bypass for the second battery connector, just going to put it on 4S for the time being.

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I drilled out the factory Arrma motor mount to 9/16 to accommodate larger pinions. I had the slightest witness mark on it from the last one and didn't want to wait until it was a real problem before doing something.


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Fitment is pretty decent, we factored a max8 in when doing the original layout. Probably could get a 85-87 length motor in this max.

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Took it to the park where we've been doing our speed runs, 45mph and barely warm to the touch on 4S. Pretty happy with that, time to blow it all apart and finalize stuff, zip ties aren't a realistic long term fastener.


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Video of the 45mph pass
 
You really should look in to replacing that busted capacitor on the Max8 if you can. Your LiPos will thank you for it and you'll get a tad better performance.
 
You really should look in to replacing that busted capacitor on the Max8 if you can. Your LiPos will thank you for it and you'll get a tad better performance.

I'll look into it. Probably beyond my electronics skillset, but my brother is a robotics engineer. I've taken circuit boards to him for repair before when the part was no longer made for replacement. I have the ability to test capacitance on my DVOM to see whether it's just cosmetic or nonfunctional, but I can't access any of the tabs to do so.
 
Corner weighted the car just to get an idea of where we are at. I built in a considerable amount of "movable" mass to be able to fine tune the car. On big power, wheelies have always been the enemy of this chassis previously it lifts the front end which baloons and explodes tires and grenades the front ring and pinion. I'll probably end up ordering the SkyRC set, but mom had these two scales around anyway for baby formula/food mixing stuff in the kitchen. There is no ability on the scale to zero it, so we took some time and cut two equal pieces of wood down to the same weight. The scales measure within 1 gram of each other. Wood is 90 grams for reference.

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1948g front, 1906g rear (including the wood)

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If I move the battery back farther by removing some of the area for the old motor mount and slipper clutch, I can get it to 1930g front and 1927g rear.

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Left to right, as expected is 1919g right, 1885g left. I doubt for what we are doing this will have any factor. I'm not getting too caught up in the specific numbers, I'm just looking for a front/rear and left/right balance idea out of this. I'll run it as is, the simplest solution is add weight to the left rear.

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@Greywolf74 I went back from the start and deleted the old images and attached them through this forum. Could you do me a favor and sample a few and see if they work right for you? They seem to work correct from all my devices.

I haven't posted in a bit, partly because our focus has been mostly on my son's 2WD Ruckus. It used to be just a quick but super tough basher for our yard but he's got more interested in going fast at the park we go to after school for just dad/son time away from everything else. We slapped the GPS from this one on it one day just curious and were surprised to see it mid 30s. We've slowly been tuning and getting faster, and last week it went an insane 47mph

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As far as we've been able to find on the internet, it's now the quickest 2WD off road RC pass ever. Any scale, any surface (the 4WD competitors denote grass/turf/sand/dirt/gravel). We'd like to hit 50 on grass before the end of the nice season here. It has more than enough power to do it, the battle with 2WD is always getting that power to the ground. If anyone else knows of anyone faster with GPS/video, please let me know we'd like to collaborate and go faster.

The 4WD has been getting a major project, and I think this picture most accurately sums it up. At this point all the final decisions have been made as far as parts selection, we are waiting on them to get here to install, take measurements, and finalize the chassis.
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@Greywolf74 I went back from the start and deleted the old images and attached them through this forum. Could you do me a favor and sample a few and see if they work right for you? They seem to work correct from all my devices.

I haven't posted in a bit, partly because our focus has been mostly on my son's 2WD Ruckus. It used to be just a quick but super tough basher for our yard but he's got more interested in going fast at the park we go to after school for just dad/son time away from everything else. We slapped the GPS from this one on it one day just curious and were surprised to see it mid 30s. We've slowly been tuning and getting faster, and last week it went an insane 47mph

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As far as we've been able to find on the internet, it's now the quickest 2WD off road RC pass ever. Any scale, any surface (the 4WD competitors denote grass/turf/sand/dirt/gravel). We'd like to hit 50 on grass before the end of the nice season here. It has more than enough power to do it, the battle with 2WD is always getting that power to the ground. If anyone else knows of anyone faster with GPS/video, please let me know we'd like to collaborate and go faster.

The 4WD has been getting a major project, and I think this picture most accurately sums it up. At this point all the final decisions have been made as far as parts selection, we are waiting on them to get here to install, take measurements, and finalize the chassis.
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Yeah man, pics work just fine :thumbs-up:
 
Late comer and catchin up on your thread, Niner. Looking good. Adapt and overcome is the name of the game. Like you are making the passes on grass. It's a challenging surface that rewards a good pass. Hang in there.

Two things, if I may:

On weighing out the car on kitchen scales. I see a "TARE" indicated. Is that a button or feature? If so, using the TARE feature should zero out the scale with the wood on it giving you a true read-out for car weights.

Regarding your son's 2WD Ruckus. Yeah, that's haulin'. Are those P-L aluminum adapters on the Raid wheels? How are they working out on that app? I've so wanted a set of those to set off the Raid wheels on my trucks. Really make that wheel pop.

Keep the shiny sides up. Cheers. 'AC'
 
Late comer and catchin up on your thread, Niner. Looking good. Adapt and overcome is the name of the game. Like you are making the passes on grass. It's a challenging surface that rewards a good pass. Hang in there.

Two things, if I may:

On weighing out the car on kitchen scales. I see a "TARE" indicated. Is that a button or feature? If so, using the TARE feature should zero out the scale with the wood on it giving you a true read-out for car weights.

Regarding your son's 2WD Ruckus. Yeah, that's haulin'. Are those P-L aluminum adapters on the Raid wheels? How are they working out on that app? I've so wanted a set of those to set off the Raid wheels on my trucks. Really make that wheel pop.

Keep the shiny sides up. Cheers. 'AC'

I was just reading your build thread, LOL. When weighing my son's 2WD, I figured out that if I put the wood on the scale before turning it on, it would zero. I don't put too much faith into the weight itself, lots of variables, but I do trust the weights compared to one another to get a F/R balance.

The raid wheels, and the Proline Badlands in general, are a godsend on grass. They seriously hook so hard that breaking stuff becomes an issue. They aren't terrible on gravel in my driveway either, and the few times I've run it down the street it seems okay. Yes, those are Proline's aluminum centers. I also have a set of Badland MX28s (the narrower, belted ones) with the shallow offset aluminum hub. They also offer them in 14mm and 17mm hex centers, but only in wide configuration. I changed out the hardware they came with for stainless. They completely ended any issue I've had with wheels. It was nice to be able to just change out a center on the Raid wheels if something went wrong, but it was still work. The aluminum center section also gives a much better "bite" for a serrated wheel nut so a lot less issues in general with big power backing off right side wheel nuts.

These are the nuts we now run exclusively.
https://www.amazon.com/dp/B07BHPN89Q?psc=1&ref=ppx_yo2ov_dt_b_product_details

We put another pinion in the 2WD, we swapped to the MX28s to try and decrease rolling resistance, and I have a few different bodies to try to get a guesstimate on what we are losing in aero this week - chasing 50mph.


Various pics of both trucks throughout having them. The skinnier ones are the belted MX28. I also have a set of MX38 we used for testing that make the 2.8s look tiny. I think the pic on the bench best illustrates the difference between the narrow offset and wide offset hubs

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Thanks, Niner. Those stainless button heads look infinitely better than the P-L carbon steel allen heads. O.K. on the serrated aluminum wheel nuts. Bookmarked them in the Speed Runner file.

Your grass runners have me re-thinking options with my MT10. It has a set of belted Trenchers that look like the bees knees for grass running at speed. Considering giving that a go instead of running it on-road.

Best to you and your son in your grass running adventures. Cheers. 'AC'
 
Not much Ecx left on that truck Chris.

There is hardly anything, really. The body shell. Which will absolutely change if we get fast enough. Such is to be expected trying to go this fast starting with an entry level RTR that was probably $150 new. Even in the last version with the Slash front and rear differential guts and all that required there was the upper and lower chassis plate, the front and rear diff housings, minor brackets here and there and that was it. When I started measuring out and designing the new chassis, it was important to me to retain an *exactly* 333mm wheelbase and 328mm track width. They are some of the most important measurements in racing and when you change them, it’s truly an unlimited prototype. The polycarbonate chassis is just a happy accident when I went out to my shop to find some scrap to mock up on - the final piece is this sheet of 3/16” 7075 T6

I would like to retain at least one OEM ECX part (more than say a screw or a clip), looks like it’s probably going to be the front and rear body mounts.

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Thanks, Niner. Those stainless button heads look infinitely better than the P-L carbon steel allen heads. O.K. on the serrated aluminum wheel nuts. Bookmarked them in the Speed Runner file.

Your grass runners have me re-thinking options with my MT10. It has a set of belted Trenchers that look like the bees knees for grass running at speed. Considering giving that a go instead of running it on-road.

Best to you and your son in your grass running adventures. Cheers. 'AC'

We really didn’t have much intention of speed running, I just have a big piece of property and we ran his around with the dogs in our dad/son time in the afternoon. It slowly progressed into getting quicker to stay out of their ability to catch and eat it, and we eventually found the limit of the 4WD one to be 2S/3S. As mine got faster, the old parts went on his. We made giant strides with weight distribution and power management on his which really made it more driveable and lent itself to more top end stuff. It was more or less a wheelie machine and it made it frustrating as hell to drive and impossible for a 3 year old. If we are lucky, one of them is running on a good day. We both enjoy the wrenching as much as actually driving. He’s been out in the shop working on my race motorcycles since he was old enough to walk. Someday when life calms down (LOL!) we will get moms 98 Cobra back to the track where it has spent most of its life.

I have a set of Trenchers and was rather disappointed on grass, not much better than the stock tires, but I got them for free with a motor so I didn’t care. I was also really concerned with launching and acceleration at the time, maybe they would do better at speed. There is an off road speed group on Facebook - please come join if you’re interested. I don’t have the roadway or the checkbook to race on road at the level I’d want to compete at. Total hats off to the guys doing crazy speeds though. Each surface has its own challenges I wouldn’t call any of them “easy” as I have heard others say.
 
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